libibery regex

[DJ Delorie]

I committed this, and mirrored it to src as well.  Tested on Linux
(but of course a new file with unique names "shouldn't affect
anything" ;).

Thanks!

To all: If you want GNU regex (from glibc, and I will strive to keep
it in sync), just include "xregex.h" in your source and libiberty will
provide you with it.  No need to do anything special, as xregex
#defines all the usual names (regcmp, etc) to "x" names (xregcmp,
etc).

> 2001-07-10  Jeff Johnston  <jjohnstn@redhat.com>
> 
> 	* Makefile.in: Add support for regex code.
> 	* regex.c: New file.
> 
> The include directory ChangeLog is:
> 
> 2001-07-10  Jeff Johnston  <jjohnstn@redhat.com>
> 
> 	* xregex.h: New file to support libiberty regex.
> 	* xregex2.h: Ditto.